The big problem with taking place the "not too distant future" is it must take place after the events of "ALIENS". Otherwise, the marines would know what they're up against on LV-426. Considering, Gateway station is orbiting the Earth so credibility on any timeline prior makes no sense.
So, post 2180, at least.
Unless, the TV series is part of the "AvP" timeline and not "ALIEN". lol
-Windebieste.